When I was a kid I used to watch a lot of sci-fi movies
in which there were genetically modified beings
to have superior bodies or intelligences.
I remember Blade Runner's replicants.
They really caused an impression on me.
Today, science is not that far from that fiction.
In 2018 in China,
twins were born whose embryos were genetically modified
with a mutation that would make them
HIV-resistant,
the virus that causes AIDS.
Since the mid-20th century
we know that the genes of all organisms
are made up of DNA molecules,
also known as "the molecules of life".
Genes determine that a plant has large or small leaves,
that an insect has wings or not,
or that a person has brown or grey eyes.
When the chemical composition of a gene's DNA changes,
the characteristics this gene defines also change.
For many years, changing the chemical composition of DNA in humans
had been very, very difficult.
But everything changed recently
when a revolutionary technique called CRISPR was developed.
The birth of the twins in China
is the beginning of a new era in modern medicine.
Genetic manipulation of human beings is already possible.
Maybe some of you already heard of this technique.
What is CRISPR?
It is much easier to modify embryonic cells with CRISPR
than to explain the meaning of the acronym.
For the curious, CRISPR means
"clustered regularly interspaced short palindromic repeats."
Unfathomable, I know.
I would simplify it like this:
if an organism's DNA contains all necessary instructions
to build that organism,
CRISPR is a text editor that can easily change those instructions.
I was one of the first scientists
dedicated to CRISPR research.
My discipline is not genetic engineering but microbiology.
I study how bacteria defend themselves against their viruses.
Yes, it's not just human beings and animals that get infected by viruses.
Also bacteria.
CRISPR is the immune system these little single-celled guys have
to defend against viruses.
In 2008, together with my colleague Erik Sontheimer,
we found out how CRISPR works.
Bacteria program CRISPR to cut viral DNA,
in that way destroy the virus and cure themselves of the infection.
In the publication of this work we proposed that this mechanism,
that evolved naturally in bacteria,
could be transplanted to other organisms
for medical and biotechnological applications.
In particular, we thought it could be used
for the modification of human genes.
Why? Because two steps are required to modify genes.
First, we have to cut the gene we want to modify.
And second, we have to repair or fix that gene
with a DNA sequence that is the one we want to introduce,
which would modify the gene.
Repairing cut DNA is relatively simple
because cells can do it themselves.
Any damage to the DNA immediately triggers mechanisms
that repair it with other DNA from a similar sequence.
This other DNA, similar to the cut DNA, is called template DNA.
And it's very easily introduced by a researcher
after cutting the DNA with CRISPR.
What was always very difficult to achieve was to develop a technique
that would cut specifically a gene among all the genes
that we have in the cells.
So, along with Feng Zhang, an expert in genetic engineering,
we decided to transport the CRISPR system from bacteria to human cells
to have it do the same it does in bacteria:
cut DNA specifically.
We program CRISPR to cut the human gene EMX1,
and we repaired it with a template DNA
introducing three modifications to the DNA.
After several tests to fine-tune the technique
we got mutant cells which had all the three modifications
that we designed ourselves.
We published our work in 2013
and because of the efficiency and the simplicity of the technology,
it was adopted by research labs
around the world.
It was the beginning of the CRISPR revolution.
This new technology has two fundamental problems.
One is technical and the other, ethical.
The first, the technical one, is that CRISPR can have "side effects".
What does that mean?
That CRISPR can cut not only the gene you want to cut,
but also another gene, therefore introducing mutations
you don't want to introduce.
To reduce this risk CRISPR is usually programmed
in several different ways.
And only those
with minimal and acceptable risk of side effects are adopted.
Taking these precautions, today CRISPR is already being used
for multiple medical applications.
Although all of them are still in an experimental phase.
For example, immune system cells can be modified
to attack cancer cells and therefore attack tumors.
Certain lymphomas and leukemias are starting to be treated
with this technology.
Research is also after new therapies
to cure genetic diseases.
CRISPR is injected to modify the defective gene
that causes that disease and correct it,
and in this way restore the functions of the organs
that are affected by the deficient gene.
In other fields, it is already beyond the experimental stage
and it's making significant impact.
In agriculture, for example, CRISPR can be used
to have crops with higher yields,
resistant to certain environmental conditions.
Livestock can be modified with CRISPR
to increase meat production
and be more resilient certain diseases.
No doubt CRISPR will be one of the technologies
that's going to help feeding the world by 2050,
with its 10 billion inhabitants.
The second problem, the ethical one, is much more serious.
Embryonic cell manipulation that would result
in the creation of genetically modified human beings
has been disapproved by all scientific academies worldwide.
Because the modification of embryos has a lot of troubles.
One is risk.
In all medical interventions there are risks.
Another problem is the lack of consent.
The person being born from embryos modified with CRISPR
can't decide.
It is possible to imagine children blaming their parents
for having introduced them traits they didn't want to have.
There's also the problem of inequality.
Not everyone will have the resources to access this technology,
which would widen the gap even more between the poor and the rich,
whether it's people or countries.
But the most complicated question is:
in which cases is acceptable the "genetic improvement" of humans?
From a religious point of view probably never.
From a medical point of view it would only be accepted
if it is possible to cure genetic diseases
that have no other treatment available.
But what will happen if future parents want to give their children advantages
by changing their genes?
Currently, doping is not accepted in athletes.
Would we allow competitions with athletes
that were genetically modified?
The case of the CRISPR twins makes it clear to us
how complex the problem is.
The researchers who performed the treatment of the embryos
justified it by labeling it as AIDS prevention,
but the rest of the scientific community
saw it as a clear example genetic improvement,
which was also carried out
regardless of the possible side effects,
and not even calculating the risks it might have.
The disapproval didn't just come from the scientific world.
Researchers involved were sentenced to three years in prison.
Today we all agree that the experiment carried out in China
was completely irresponsible and premature.
But it made it clear to us that genetic modification of humans
is possible and that it will certainly be part of the world to come.
It was the take-off of a ship to a future, and there is no turning back.
While there's still a long way to go to know what genes
we have to change in people
to create the "replicants" of Blade Runner,
CRISPR gave us the tool to do it
when we have that knowledge.
But we can't wait arms crossed.
Now it's time to start discussing and debating
how we are going to use this new technology.